Our program involves the means of presentation of medical images from a wide range of modalities. The research, consisting of six projects, concern 3D and 2D display for diagnosis and for planning of radiotherapy. For 3D display we will investigate methods for fast, interactive 3D visualization of medical image information, directly from the image intensity data. We will also investigate a number of approaches for visualizing the spatial relationships among 3D information from two imaging modalities. Qualitative clinical evaluation will support these investigations. Object definition methods that operate in both 2D and 3D and which are based on multiresolution image descriptions will be developed, so as to support the 3D display investigation. Here evaluation will be based on the time to produce an accurate definition of an object of clinical interest. For 2D display we will investigate contrast enhancement, workstation design for effective navigation through large image sets, and fundamental aspects of visual perception of contrast in grey-scale images, leading to effective display. The visual perception research will focus on the relation of an image's spatial structure on the perception of contrast in that image. The contrast enhancement technique of contrast-limited adaptive histogram equalization will be investigated for a wide range of clinical applications, and it will be heavily evaluated and improved for radiotherapy treatment applications. The workstation research will compare the use of traditional and electronic means of display and will develop prototype workstation functions. Controlled observer studies will form the basis of all the 2D perception and display research.